Metal nanostructures have uses ranging from catalysts and adsorbants to components of various optoelectronic devices. The properties of such nanostructures (e.g., their catalytic reactivity or their electrical and optical properties) vary, e.g., depending on their composition, size, and shape. Methods for simply and reproducibly producing metal nanostructures, e.g., of different sizes and/or shapes, are thus desirable. Methods for simply and reproducibly producing metal nanostructures containing minimal levels of undesirable contaminants are also desirable. Among other aspects, the present invention provides such methods. A complete understanding of the invention will be obtained upon review of the following.